For joining your vessel in Ushuaia, it is likely that you will be meeting your ship at the Puerto de Ushuaia.
The ships exact location in port is often controlled by the port authorities and they will only allocate a docking position a few days before. You will be informed as soon as possible of their exact joining location.
Any changes will be communicated to you before your voyage start date. Make sure you make a note of the ship’s number found in your confirmation email in case of any problems on the day.